Electronic structure, Dirac points and Fermi arc surface states in three-dimensional Dirac semimetal Na<sub>3</sub>Bi from angle-resolved photoemission spectroscopy

Electronic structure, Dirac points and Fermi arc surface states in three-dimensional Dirac semimetal Na₃Bi from angle-resolved photoemission spectroscopy

Liang Aiji¹, Chen Chaoyu¹, Wang Zhijun¹, Shi Youguo¹, Feng Ya¹, Yi Hemian¹, Xie Zhuojin¹, He Shaolong^{1, †,}, He Junfeng¹, Peng Yingying¹, Liu Yan¹, Liu Defa¹, Hu Cheng¹, Zhao Lin¹, Liu Guodong¹, Dong Xiaoli¹, Zhang Jun¹, Nakatake M², Iwasawa H², Shimada K², Arita M², Namatame H², Taniguchi M², Xu Zuyan³, Chen Chuangtian³, Weng Hongming^{1, 4}, Dai Xi^{1, 4}, Fang Zhong^{1, 4}, Zhou Xing-Jiang^{1, 4, ‡,}

Fermi surface and band structures taken on the (001) surface of Na₃Bi by using He Iα (21.2 eV) light source. (a) Sketch of the momentum position of the 3D bulk Dirac nodes in the bulk Brillouin zone and their projections onto the surface Brillouin zones on the (001) and (100) surfaces. The red dashed line connecting the two Dirac cones on the (100) surface represents nontrivial surface state with an arc structure. The atomic structures of both the (001) and (100) surfaces are also drawn. (b) Fermi surface covering a large momentum space of the first and second Brillouin zones on the (001) surface. (c) Band structure along the momentum cut as marked by a red line in (b). (d) Calculated band structure along the same momentum cut as (c). (e) Fine mapping of the Fermi surface around the point on the (001) surface. (f) Band structures measured along seven momentum cuts labeled as red lines 1 to 7 in panel (e). The red dashed lines are fitted curves considering the Dirac cone shape. (g) Three-dimensional view of the evolution of Fermi surface and constant energy contours at different binding energies. The red lines are the guide to the eye. The band images are all obtained by the second derivative of the original data with respect to the energy.